Technical Field
The present invention is related to a seatback frame provided to a seatback of a vehicle seat, and a vehicle seat.
Related Art
A vehicle seat described in Japanese Patent Application Laid-Open (JP-A) No. 2012-136058 includes a seat frame that is a frame of a seat unit on which an occupant sits, and a seatback frame supported by the seat frame. The seatback frame includes side frames including pipes extending along the up-down direction and disposed separated at the left and right, and a lower portion connecting member that is formed of sheet metal disposed spanning between lower portions of the left and right side frames and connects the left and right side frames together. The lower portion connecting member includes a rear wall portion connected to and supported by the side frames, and a front wall portion extending forward and downward from an upper end of the rear wall portion. A front face of the front wall portion is inclined so as to be parallel to an extension direction of the pipes of the side frames, or to face upward with respect to this extension direction, in side view. During a rear end collision, a sense imparted to an occupant of being struck by the lower portion connecting member is thereby alleviated. Note that JPA-No. 2012-136059 describes a similar vehicle seat to that described above.
In vehicle seats such as that described above, when an excess load is input to the lower portion connecting member from an occupant moving under inertia toward the seat rear side during a rear end collision, the lower portion connecting member deforms toward the seat rear side, and a tensile load is generated at fixing portions between the lower portion connecting member and the left and right side frames. There is accordingly a possibility of the fixing portions being damaged, and of load being transmitted to other members such as the left and right side frames, such that the other members are damaged.